Wind turbines may be operated in a de-rated mode where the wind turbine is controlled to produce an amount of power which is lower than the amount of power that can be produced considering the available wind power. The purpose of operating the wind turbine in a de-rated mode may be to establish a power reserve that can be released if needed.
The de-rated wind turbine may be requested to ramp production up very fast to full production, e.g. in order to meet an increased power demand at the grid. The full production may be the maximum production being possible with a given available wind power. The ramping demand may be in the form of an external power reference from a grid operator or other external source.
The fast ramping of power up to full production may lead to various undesired effects such as undesired variations in the produced power.
Accordingly, there is a need to improve the wind turbine's capability to handle power ramping demands.
US2012139247A1 discloses a wind power plant, including a generator driven by a rotor for generating electrical power and a controller that includes a pitch module for adjusting a pitch angle of blades of the rotor. The controller has an input for a required power reserve and determines a target pitch angle depending on an operating point of the wind power plant. A secondary pitch controller is also provided, which includes a detector for available power and a dynamic offset module. Input signals for the available reserve power determined by the detector, the required reserve power and the generated electrical power are applied to the dynamic offset module, which is designed to determine a value for a pitch angle offset. An activation element varies the target pitch angle by the pitch angle offset.